Wound-type core for a transformer or the like



Oct. 13, 1959 ks. HoRELlcK ET AL 2,908,879

WOUND-TYPE CORE FOR A TRANSFORMER 0R THE LIKE Original Filed ug. 14, 1952 5 Sheets-Sheet 1 gl a Oct. 13, 1959 s. HoRELlcK ETAL 2,908,879

woUND-TYPE CORE FOR A TRANSFORMER 0R THE LIKE 5 Sheets-Sheet 2 Original Filed Aug. 14, 1952 INVENTORS SAMUEL HORELICK & Jos-1N J. ZlMsKY )lv-fu] and? @aq 0ct. 13, 1959 s. HoRELlcK ETAL 2,908,879

WOUND-TYPE CORE FOR A TRANSFORMER OR THE LIKE Original Filed Aug. 14, 1952 5 Sheets-Sheet 3 INVENTORS SAMUEL HoRELlcK 8. JOHN J. ZlMs @wig Oct. 13, 1959 s. HoRELlcK ETAL 2,908,879

wouND-TYPE CORE FOR A TRAN'sFoRME-R 0R THE LIKE 5 Sheets-Shedl 4 Original Filed Aug. 14, 1952 .wmf

SAMUEL HORELLCMS` JOHN J. ZIM KY %%M" l JJ 6l 0 Oct, 13, 1959 `s. HoRr-:LICK ETAL 2,908,379

WOUND-TYPE CORE FOR A TRANSFORMER OR THE LIE Original Filed Aug. 14, 1952 5 Sheets-Sheet 5 "mgm" Immun lNVEN-roRs SAMUEL HOFQELCKl JOHN J. Z|MSKY 6W, auaul United States Patent C WOUND-TYPE CORE FOR A TRANSFORMER OR THE LIKE Samuel Horelick, Pittsburgh, and John J. Zimsky, Bridgeville, Pa., assignors to McGraw-Edison Company, a corporation of Delaware Continuation of application Serial No. 304,346, August 14, 1952. This application October 24, 1956, Serial No. 620,784

2 Claims. (Cl. 336-210) This invention relates to a new core of the wound shape for transformers or the like. More particularly, it relates to new cores for larger various sizes of transformers and the like employing relatively interchangeable or standardized corner parts.

This application is a continuation of application Ser. No. 304,346, tiled August 14, 1952, now abandoned, entitled Wound-Type Core for a Transformer or the Like.

In the art of transformer and similar cores, it is usual to use either hot rolled or cold rolled ferromagnetic strip material such as oxide coated silicon steel for the core metal. Further, it is usually desirable to produce such cores from core steel so that the flow of magnetic flux is in the direction in which the core steel has been rolled. 'In order to minimize core loss, particularly at the corners ofthe cores, the art has frequently turned to the use of wound-type cores in which the bent laminations are generally parallel to the axis of the window of the core and tangent to the winding turns. These wound-type cores avoid the usual difficulty at the corners inherent in :the construction and use of laminated-type cores in which the at laminations are generally normal to the axis of the core window. However, it has not usually been considered practicable to produce wound-type cores for transformers, such as power transformers, and the like, hav- -ing relatively higher kva. ratings.

In this invention, a wound-type core can be produced economically for such power transformers of relatively higher kva. ratings and the like, thereby retaining the other advantages of such wound-type cores for ythe larger equipment. Moreover, by means of this invention, the 4corner pieces of the respective laminations are so conystructed' that wound-type cores of any of many differentV sizes and dimensions may be made therefrom. ln this Way, and to such extent, there is a desirable standardization of parts. Further, for cores of given dimensions, the straight reaches or parts of the laminations extending between the corner parts are substantially equal in length in each side and on opposite sides of any of the new cores. As a consequence, a variety of transformers and the like of different ratings and sizes may be assembled by relatively unskilled workmen using a minimum stock of lamination parts for said cores.

Other objects and advantages will be apparent from the following description, and from the drawings which are diagrammatic only, in which,

Fig. il is a' view in front elevation of a coil of'wound ferromagnetic strip to be used in one fabrication of corner parts for cores for transformers or the like in accordance with the teachings of this invention;

Fig.v 2 is a View in front elevation of the coil shown in Fig. 1 showing the coilinlg mandrel, a mode of fastening the coil thereto, which coil llas been drilled in the indexing positions;

. Figs?) is ay View, partly in cross section, taken'along line III-lll of Fig. 2;

' 1-lig.. 4 -is auview in front elevation of the coil shown ice 2 in Fig. 2 after it has been cut into quadrantal sections;

Fig. 5 is a View in front elevation of an initial stacking step for such a quadrantal section;

Fig. 6 is a View in front elevation of a stacking position of the said quadrantal section subsequent to that shown in Fig. 5; y

Fig. 7 is a view in front elevation showing a mode of clamping and shaping the quadrantal section shown in Fig. 6, preparatory to annealing;

Fig. 8 is a schematic view showing the assembly of a lower portion of a transformer core made in accordance with this invention using two of said quadrantal sections for the two lower corners thereof with a conductive winding surrounding each of the core-winding legs abov'e said corners;

Fig. 9 is a schematic view in front elevation showing the core of Fig. 8 completed with the employment of two further quadrantal sections for the upper two corners thereof;

Fig. 10 is a view in front elevation of a substantially completed power transformer embodying a core of generally cruciform cross section made in accordance with this invention;

Fig. 11 is a View in cross section taken substantially along line Xl-XI of Fig. 10;'

Fig. 12 is -a schematic view of a modified shell type transformer utilizing two cores made in accordance with this invention;

Fig. 13 is an illustration of a modified core type threephase transformer utilizing three cores made in accordance with this invention; and

Fig. 14 is a schematic view of a 5legged core for a three-phase transformer which may be constructed ernploying four individual cores made in accordance with this invention.

As shown in Fig. 9, a new core 10 is provided for the conductive windings 11, each of which may comprise a single winding or a plurality of windings of conventional nature. Such windings will usually be preformed before assembly with core y10. In constructing such a transformer assembly with preformed windings ill, as shown in Fig. 8, the lower portion of core 10 is constructed and the windings 11 positioned thereon prior to the completion of the core by adding the upper portion thereof as shown in Fig. 9. The terms lower and upper are relative inasmuch as the cores of this invention, as is the case with other transformer cores, may be used in vertical or horizontal or other desired position.

Core 10 will usually be made of conventional closed generally rectangular shape having a pair of opposite, substantially straight, parallel winding legs 12 which usually are placed in a vertical or horizontal position. Either one or both legs 12 may actually be used as a winding leg and be linked by passing through the window of a winding 11. Thus, in the transformer illustrated in Fig. 9, each of the winding legs 12 is linked with at least one winding 11. On the other hand, in the moditied core type of transformer diagrammatically shown in Fig. 12, `in which the cores 10 may each be made in accordance with this invention, only one of the winding legs 12 of each of the cores 10' is linked to a winding 11. The other or outer winding legs 12 of the side-byside cores 1li in the Fig. 12 structure do not pass through any winding.

In core 110, the winding legs 12 are yoked by the opposite spaced parallel sides 13 completing the four sides of the generally rectangular core shape. These `sides 13 17 of the core. 'strips or pieces 18 of ferromagnetic material in the legs .13 and straight strips -or pieces 19 of ferromagnetic ma- Hn ,man A "i, inclusive. l Since the quadrantal corner sections 14 are the corners of core and usually have the same number of laminar pieces of ferromagnetic strip -as the adjoining straight sections of core 10 in the legs 12 and 13, core 10 comprises a plurality of single closed concentric rectangular laminations or turns `15 extending from the edge of the windowr16 in the core to the outer edge of periphery Each lamination 15 comprises straight vterial in the legs 12. The adjoininlg straight pieces 18 and 19 are each connected to complete the magnetic circuit turn by an arcuate or curved corner piece 20. Each corner piecef20 is a piece of core steel strip in the shape vof an angle having a longer side -201 and a shorter side '20S' with an included dihedral angle between said sides 201 and 20s of approximately 90. In some cases, it may `be desirable to form the laminations of the lower portion illustrated in Fig. 8 out of single U-shaped members.

kbent into a sharp right-anglek at theV appropriate location along each piece of stripto provide, when assembled with the other bend strips, a corner having the new -characteristics described in connection with the quadrantal corners f14.

Each of the corner pieces 20 makes two butt joints with the adjoining ends of the adjoining straight'pieces 1`8 and 19 respectively. Thus, inthe upper left-hand portion of Fig. 9, side 2th, which on the innermost lamination 15 extends vertically downwardly, abuts the upper Vend of straight piece 119 on'that side'of core 10 and the side 20s of the same corner piece 2t) makes ya butt joint with the left-hand end of the upper innermost straight piece 18. Moving outwardly from the axis 221 of window 16, which axis is normal to the surface of the drawing, the long sides 291 of the corner pieces in each quadrantal section 14 are staggered, that is, the long sides'201 of successive pieces 20 are on opposite sides of a plane bisecting the included angles of those pieces. Fui-ther, in each turn 15, the sides 201 of the respective corner pieces `20 extend in the same rotational direction about axis 21. VBy this means, the respective butt joints in successive laminations '15 are staggered or otfset relative to the corresponding joints on adjoining laminations :115 to the extent approximately of the difference between the lengths of the respective sides of the respective corner pieces 2t) in that lamination.

Since the corners 14 will usually be alike and the corner pieces in each corner 14 `are substantially quadrantal relative the other corner pieces in the same corner, all of the straight pieces 18 may be made of the 'same length for any core to be provided with the same yoke width lbetween the winding leg sides 12 of the core. Likewise, all of the straight pieces 19 for` all of the laminations 15 are equal in length, not only for the given core, but for any other core to be provided with the same winding leg height between the yoke leg sides 13 of the core. Whenever both height and width of a Ycore made in general accord with core 101s to be changed, respective straight pieces corresponding in purpose -to straight pieces 18 and 19 and in size to the desired changed dimensions, may be provided for use with similar or identical quadrantal corners 114 to readily enable the new size of core to be made.

Since the straight laminationl pieces can very readily be made on the usual shearing and/or slitting machines from ferromagnetic steel strip of the appropriate width and thickness, the practice of this invention'immediately vivi/itiesY ,a means for, making@ ,wide range. of transf formers and the like of relatively higher ratings such as power transformers of 500 Ykva. and over, by the use of a stock of relatively few sizes of straight pieces and the use of curved quadrantal corners of corresponding width and thickness. When any entire` core made in Iaccordance with this invention has'a corresponding number of turns of the same width and gauge,l the quadrantal corner "sections of that widthV and gauge of metal will serve for an even increased number of different sizes of the new corres. Y i The teachings of this invention can be used in the construction of new cores having a generally cruciform shape such as is illustrated in Fig. ll, the corners of which may be made as shown in Figsfl to 7. The employment of cores which are cruciform in cross section is in and of itself an old expedient to obtainya more efficient space factor. The new core 3i) of this invention which is illustrated in Figs. l0 and ll has thesame physical structure substantially as core '.10 of Figs. 8 and 9 except that core 10 may be made'of a uniform width of core strip. Y Core 3e is similarly linked with windings 31 through the windows of which winding legs '32 pass. The stepwise lateral variation of the width of thefstrip required to make successive concentric laminations I33 for core 30, as shown in Fig. ll, is the chief physical differencerin construction from any core 10 in which substantially all of the laminations 15 thereof are substantially equal in width from edge to edge.

In order to hold the respective parts of the cores of this invention together, a Variety of conventional Vmeans may be employed. Thus, in the case of core 30, the laminations 33 are bolted together around the entire periphery of the core by bolts 34 extending completely throughl the laminations and cooperating with nuts 35 which threadably engage the respective bolts. Each of the bolts 34 is insulated by an insulating sleeve 36 where it passes through the laminations. Further, as shown in Fig. l0, the corners 40 may be locked in the completed new core by a bolt 34 passing through the drilled opening near theV edge of the longer sides of the corner pieces in registry kwith a similar opening in the straight pieces interleaved with such longer sides. In general, the shorter sides Yof the respective corner pieces are adequately held inthe final -assembly by the frictional pressure exerted on each shorter side by the longer sides of the adjoining corner pieces in the same corner. It will be noted thatin each corner the respective edges of the respective corner pieces are generally in respective planes, the planes being preferably normal to the width of the core in which the ends of the corner pieces lie, and, such planes at the ends of a single corner on adjoining sides of the core being generally at right angles. An insulating spacer 37 tits tightly against the sides of the innermost and outermost laminations to insulate them from the steel straps 38 between the respective pairs of which the laminations are clamped along each side thereof by the respective bolts 34 and nuts 35. 'Ihe outermost straps 38 lalong the outside of the winding legs 32 are provided with stud ends 39 for mounting in the transformer frame. over, the windings 31 are blocked up in immovable relation to winding legs 32 and the rest of core 30 in conventional manner so that neither the mechanical nor electrical stresses encountered will shift any part of the transformer or of the new core therein. The respective bolts'34 and nuts 35 Vnot only hold the pieces in each lamination and the respective laminations in cooperating relationshipy but also clamp successive laminations tightly together to effect an eicient magnetic ilux cross-over relationship between successive lamination turns 33, particularly across the respective butt joint areas of each lamination. p Y

In order to construct the quadrantal corner sections 40 such as would be suitable for core 30, a width of ferromagnetic steel strip corresponding in Vwidth to the width of the innermost laminations 33 in therst step' A" Moreof. the cruciform cross section thereof, may have its end tack-welded to a hollow rectangular coiling mandrel 41. Mandrel 41 may be welded to a plate 42a adapted to be bolted to a flange plate 43a integral with the shaft 44a of a conventional coiling machine which is not illustrated. After winding enough of said width of strip to provide for that part of the four corner sections 40, which is to correspond to step A, the strip is severed in a conventional manner and a second strip corresponding in width tothe step B width may be tack-welded to the end` of the prior length of strip coiled around mandrel 41. Subsequently appropriate lengths of strips of appropriate widths are sequentially coiled for steps 0, D, E, F, and G. The final end of the length of strip for forming step G may be tack-welded after it is severed, leaving mandrel 41 with a coil 42 of turns thereon -as shown in Fig. l. Whenever a core made in accordance with this invention is of uniform width from edge to edge of the strip throughout, only a single width of strip of appropriate gauge and continuous length will be` coiled about a mandrel such as mandrel 41.

Coil 42 may be then centrally drilled along the axis of its cardinal radii 43 and bolted respectively to the faces 44 of mandrel 41 by bolts 45. At the same time, holes 46 may be centrally drilled along a plane passing through the vlongitudinal axis of mandrel 41 and generally bisecting the angle between a-djoining ones of the cardinal radii 43 because rectangular mandrel 41 inthe illustration shown has a square cross section. These holes 46 lie along what may be called the four indexing planes or positions of the respective turns in coil 42. Such indexing plane positions may pass through each of the respective exterior corner edges of a rectangular mandrel which crimp or bend the coiled strip as it is wound.

After the fastening of coil 42 to mandrel 41 and the drilling of holes 46 along the indexing planes, plate 42 may be unbolted from plate 43a and coil 42 mounted adjacent a saw or cutter to sever the turns of coil 42 along the respective planes 47 parallel and adjacent to transverse planes through the respective cardinal radii 43. Usually the severance planes 47 where all of the turns are cut will be offset but relatively close to the respectively adjacent radius 43. In this way, all of the turns of coil 42 `are converted into four quadrantal sections substantially identical to each other. In each section destined for a corner of a core of this invention, the distance along the strip making up the pieces in each section varies on the two sides of the indexing position or bend to predetermine the difference in length between the long and short sides respectively of the said pieces and eventually of the corner pieces. If a cylindrical mandrel is used with index positions drilled bisecting the cardinal radii, the severing of turns thereon may be made along a radial plane normal to the mandrels surface.

Upon severance of the turns of coil 42 along the planes 47 there is suflicient elasticity in each of the pieces in each section to cause the sections to spring into the general form illustrated in Fig. 4. Thereupon, -a steel pin 48 may be shoved into hole 46 of the respective quadrantal sections to keep the pieces in each section in alignment while the respective bolt 45 holding said section to mandrel 41 is loosened andv removed. Then the turns of the respective section on pin 48 can readily be transferred by a workman to a clamping and forming block 49 having -a die portion 50 thereon. Pin 48 lits into a hole 51 in die portion 50 to keep the pieces of each section in vertical alignment on block 49 While permitting rotation of alternate pieces about the axis of pin 48.

Preferably, in the new cores of this invention, successive laminations will have the respective joints thereof staggered relative the joints of adjoining laminations. Under these circumstances, the pieces 52 from the respective quadrantal sections will have the alternate ones thereof rotated 180 about the axis of pin 48 relative to successive such pieces, bringing the partially shaped assemblage into the position shown in Fig. 6 with the indexing plane or bend of the respective pieces rising directly and vertically above the apex of die portion 50 which has a dihedral angle'between the sloping sides thereof equal to the approximate angle desired as the included angle of the finally shaped and annealed pieces 52.

An upperv die block 53 may be placed over the pieces in the position shown in Fig. 6 and has openings 54 therethrough which slide over clamping bolts 55 alixed to block 49 and a central drilled hole 56 which slides over pin 48. An upper die surface 57 is adapted to shape the outermost of the pieces 52 in each of the sections. By turning down on the nuts 58, block 53 clamps the pieces 52 against block 49 and die portion 50 giving them their final shape so that when annealed in conventional manner while so clamped, the pieces 52 are converted into preshaped corner pieces, such as the corner pieces suitable for employment in making core 30, with the electrical properties of the corner pieces restored by the annealing. Although the illustrations in the drawings show relatively few laminations, it is understood that this showing is but diagrammatic and that in actual practice the `requisite number of pieces for the desired number of laminations in `the final core Will be coiled, shaped and annealed. Further, if desired, a jig may be used in place of pin 48 to align the bends of the respective pieces, such as pieces 52, over the apex of the die portion 50 in which case no holes corresponding to holes 46 will have to be drilled in the turns of the coiled strip.

In addition, in the assembling of each lamination and the strapping of the respective laminations, as in the case of core 30, the holes drilled along the cardinal radii 43 may be utilized for the passage of a bolt 34 making it unnecessary in such case to drill any additional holes through the corner pieces in order to achieve the necessary assemblage of the respective corner pieces and straight pieces in interlaminated arrangement as illustrated in Fig. l0.

In the three-phase transformer embodiment illustrated in Fig. 13, a plurality of the new cores made in accordance with this invention, may be employed. Thus, inner cores respectively numbered 60 and 61 may be placed side by side, the adjoining winding legs 62 and 63 of which may be linked with a single winding 64. Both cores 60 and 61 are enclosed within an exterior core 65 having winding legs 66 and 67. The legs 66 and 67 are respectively in side-by-side relation to the outer winding legs of the cores 60 and 61 for linkage again respectively with windings 68 and 69. It will be noted that the straight pieces in all of the winding legs of all of the cores may be of equal length as shown. Further, the corners of the cores 60 and 61 nesting with the respective corners of core 65 may be constructed, if desired, by the winding of a single coil by the mode generally illustrated in Figs. l to 7. While the straight pieces in the yoke sides of cores 68 and 61 will generally be of the same length, the straight pieces in the yoke side of core 65 Will be much longer as shown in Fig. 13. Preferably, the corner pieces of the respective cores illustrated in the threephase core assembly of Fig. l3 will be asymmetrical in having one of the sides of each of the corner pieces longer than the other in the manner generally illustrated, for example, in Fig. 9. Thus, in general, insulated bolting would be employed through the overlapping portions at the joints immediately at the ends of the straivht pieces in legs 62 and 63. Similarly, there would be such insulated bolting at the other end of the corner pieces adjoining such straight pieces in legs 62 and 63. Wherever the joints in the cores 60 and 61 are in general alignment with the joints in core 65, the same insulated bolting means may be employed for the entire joints respectively so aligned. As will be well understood, the turns of the respective cores 60,

that may be desired. Y

i In the Fig.V 14 diagrammatic embodiment, a plurality 'of' individual new cores 70 may be constructed and placed in side-by-side relation to create a -legged core. The compositevinternal three legs 71 of the Fig. 14 'core may respectively be linkedwith at leastthree Wind- `ings 72 to provideV a three-phase core. As will be Well understood,l the windings illustrated -in Figs. 13 Yand 14 may be linked with the respective cores in the same manner as illustrated in the case of the embodiment 'shown-in Figs.,8 and 9. i

Although one new Vmode of constructing the 90 'cornersemploys a mandrel about which suitable strips is coiled, other modes of construction may be employed particularly where the new corner pieces are sharply angled Yas in ythe case of right-angled angles. Thus, corner pieces may be made as a part of `the practice of this invention which are notbegun by the coiling of strip on a mandrel. Instead, strip stamping or shear- 'ing and angle-formingl means may be provided for that purpose. Corner pieces may be so made VWithout departing from the teaching of the present invention. y Moreover, such corners may have alternate cor/ner pieces with two, longer sides While the alternate interleaved corner pieces in the same corner have two shorter sides. Then, the iinal new core `assembly would have the longer-sided corner pieces respectively in the same lamination turn in diagonal corners with the shorter-sided corner pieces in the same lamination turn in the diagonal corners adjoining the longer-sided corner pieces. Y

Still further, although it is preferable in constructing new rcorner pieces in accordance withvthis invention to anneal them after any cutting or shearing operation is performed thereon, a higher loss level is'permissible in higher rating transformersv and the like, which in some cases will permit of annealing the corner piecesin their final shape before the cutting or shearing'thereofis performed.

vVarious other modifications may be made in the de,- tails of this invention without departing from the spirit thereof or the scope of the appended claims.

l What we claim is:

1; A hollow, generally rectangular, magnetic core of 8 ilatwisebent laminationsi, said core having separate, 'iden'- tical corner units at each *ofV the corners thereon each of lsaid cornerk units lcomprising a pluralityl of compactly nested, annealed-inaplace corner lamination pieces of magnetic material, each of said corner pieces being flatwise bent through an angle of approximately ninety degrees, said corner pieces having a preferredl grain orientation longitudinally thereof and being free from strains resulting from bending or shearing operations performed thereon, said corner pieces progressively increasing in length in a radially outward direction, odd-numbered corner pieces extending beyond the ends of even-numbered pieces at one'end of each said corner unitp'and even-numbered corner pieces extending beyond the ends of odd-numbered pieces atthe other end ofVsaid corner unit, whereby said corner pieces maybe interleaved with any length leg and yoke lamination pieces to form a core of any desired size, said core having opposed winding leg portions and opposed yoke portions connected by said corner units, each of said leg portions embodying a plurality of straight lamination pieces of magnetic material of substantially equal length interleaved with the corner pieces of two of said corner units, and each said yoke portions embodying a plurality ofl straight lamination pieces of magnetic material of substantially equal length interleaved with the corner pieces of two adjacent corner units. v

2. A magnetic core in accordance with claim l wherein each of said lamination pieces is formed with ahole adjacent the end thereof and the holes in thefinterleaved corner pieces and straight pieces are in register, andincludring means extending through said registering holes for clamping the interleaved endsV of said straight pieces and corner pieces together.Y i i i References Cited Vin tile of this patent UNITED STATES PATENTS 

